In general, a vehicle black box operates in driving mode and parking mode depending on the start-up state of a vehicle.
Upon driving mode, a screen is stored in accordance with three types of recording methods, such as normal permanent recording, permanent impact recording, and manual recording.
Permanent recording is a method for capturing all images in a specific time unit and storing the images in a permanent recording folder while driving. Permanent impact recording is a method for capturing an image at a previous specific time and an image at a subsequent specific time on the basis of an impact time when an impact of sensitivity or higher set by a user is generated (hereinafter referred to as an “impact event”) and storing the images in a permanent impact folder. Manual recording is a method for capturing an image at a previous specific time and an image at a subsequent specific time on the basis of a point of time at which a specific button is pressed and storing the images in a manual recording folder.
In the permanent impact recording, an acceleration sensor is chiefly used as an input device so as to sense an impact event. An impact event sensing algorithm determines whether a difference between the instant size of each of acceleration values in the X, Y, and Z directions of the acceleration sensor and an average size during a recent specific time is a value of sensitivity or higher set by a user, and determines the difference to be an impact event if the value of sensitivity or higher is output.
The impact event sensing algorithm using an acceleration sensor determines whether a moment acceleration value is a set value or higher. However, an unwanted accident attributable to an impacted road or a speed bump depending on a road condition in which the vehicle is driven and an invalid impact event (i.e., false positive) when a vehicle door is open/shut or a trunk is closed while the vehicle stops are generated in addition to a valid impact event (i.e., true positive), such as the collision of a vehicle that a vehicle black box has originally attempts to sense.
A storage space of a limited size is filled with the image file of an invalid impact event because an image of a specific time is stored in the permanent impact folder when such an invalid impact event is generated. Accordingly, there were problems in that it is difficult for a user to find out an actual required valid impact event and the lifespan of SD card type flash memory is reduced because a large image file that does not need to be actually stored continues to be stored.
Furthermore, if a folder of a limited size is filled with many invalid impact events, the oldest image file is overwritten. In this case, there was a problem in that a valid impact event may be overwritten.